Method of coating the internal surface of a pipeline with a cement-sand mortar and a device for effecting same

ABSTRACT

According to the method of coating the internal surface of a pipeline with a cement-sand mortar, a layer (4) of the mortar is formed on said surface and is pressed and held by a flexible hose (5). Before the flexible hose is pressed to the mortar layer (4) the flexible hose (5) is turned out and placed simultaneously with the formation of the mortar layer. The device effecting the method as claimed has a cement-sand fed system (11), a piston (3) arrnged in the pipeline (1) with an annular clearance (12) to distribute the mortar layer on the internal surface of the pipeline, a chamber (13) accommodating the flexible hose (5) and communicating therewith by a flowing medium feed system (15), said flowing medium serving as a means for feeding, turning out and pressing the flexible hose (5) to the mortar layer (4) formed on the surface of the pipeline.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the construction and maintenance ofpipelines, and, more particularly, to the method of coating the internalsurface of a pipeline with a cement-sand-mortar and a device foreffecting same.

2. DESCRIPTION OF THE PRIOR ART

Today, there are known in the art the method and device for coating theinternal surface of pipelines with a cement-sand mortar (cf. e.g., abooklet by the U.S. Ameron company "A Drawing Method of RestoringPipelies". Instructions A-101 and A-102).

In accordance with this method and device a layer of mortar is appliedon the internal surface of the pipeline in the following manner. Apiston is installed in a pipeline with an annular clearance. Prior, thepiston the pipeline is filled with a cement-sand mortar. With the aid ofa rope the piston is drawn along the pipeline, the mortar is forced outinto the clearance between the piston and the pipeline forming a layer.Due to viscosity this mortar is retained on the pipeline wall and oncesolidified, forms a protecting coating.

However, this method can be used for coating the internal surface ofpipelines with up to 250 mm in diameter, because in larger dia.pipelines the formed coating is not held on the internal surface due toan insufficient paving and transverse strength of the layer.

Summary of the Invention

It is the main object of the present invention to develop a method anddevice for coating the internal surface of a pipeline with a cement-sandmortar which would ensure a reliable bond thereof with the surface ofthe pipeline, thereby creating a durable coating and protectingpipelines of different diameters.

The main object of the present invention is accomplished by a method ofcoating the internal surface of the pipeline with the cement-sandmortar, comprising the formation of a mortar layer on the inside of thepipeline by way of feeding and distributing said mortar on the internalsurface of the pipeline by means of a moving piston, according to theinvention, the formed mortar layer is pressed and held on the pipelinesurface with the aid of a flexible hose which is held fixed by itsturned-out end to the pipeline and, as the hose is gradually turned out,it is fed to the pipeline being pressed to the mortar layer, the hosebeing laid simulateneously with the formation of the mortar layer.

According to the invention, the flexible hose is fed, turned out andpressed to the formed mortar layer by a flowing medium which is fed tothe cavity formed by the turned out portion of the hose. As this occurs,the flowing medium and the portion of the flexible hose being turned outmake up a means for moving the mortar and piston along the pipeline.

The holding of the mortar on the pipeline surface by means of theflexible hose prevents the formed coating from falling off the pipelinewall and this, in turn, makes it possible to increase the thickness ofthe layer of the coating being formed over one stroke of the piston.

The flexible hose improves the quality of the coating because the formedlayer is subjected to pressure of the flowing medium (air) through thebase which increases the coating strength. The quality of the coating isalso improved because the mortar layer is hardened in the hermeticvolume and does not crack. By virtue of the flexible hose the flowingmedium also serves as a mover for the piston which appreciablystreamlines the technology of applying the coating, reduces the amountof equipment used for applying the coating.

Once the mortar has hardened on the pipeline surface, the flexible hosemay be taken off by feeding the flowing medium between the hose and themortar layer and, having secured the second end of the hose to thepipeline, feed it to the next portion of the latter as the hose isgradually turned out.

Removing the hose from the formed coating, upon its solidification,enables one to cover with one hose the subsequent portions of thepipeline over one stroke of the piston. The hose is removed as itsimultaneously moves to the neighbouring section which fact streamlinesthe technology of forming the coating and makes the equipment lesssophisticated.

It is advisable that longitudinal strips of electrochemical solublealloy be pressed in the layer of the mortar held by the flexible hose,thereby making it possible to additionally protect the pipeline againstan aggressive medium. The technology of mounting the strips in thepipeline and obtaining a prior art cathode protection of the pipeline isupdated.

It is expedient that a tube be arranged in the flexible hose. This tubealong which the mortar is pumped to the piston should be fed to thepipeline together with the hose.

The arrangement of the mortar feed tube in the flexible hose makes itpossible to coat long pipelines, each pipeline having one opening. Thishelps improve the compact size of the device and its operatingconditions, and decrease the force necessary for moving the piston.

One can remove the remaining mortar in the pipeline by feeding anelastic plug therethrough using an air flow with a subsequent washing ofthe pipeline with water.

To effect the method as claimed use is made of the device for coatingthe internal surface of a pipeline with the cement-sand mortar, whichcomprises a cement-sand mortar feed system and a piston disposed in thepipeline with an annular clearance to distribute the layer of mortaralong the internal surface of the pipeline which, according to theinvention, is furnished with a chamber mounted behind the piston in thedirection of mortar application, said chamber accommodating a flexiblehose whose end has an arrangement to secure it to the airplane, and aflowing medium feed system communicating with said chamber, said flowingmedium serving as the means for feeding, turning out and pressing theflexible hose to the mortar layer formed on the surface of the pipeline.

The arrangement for securing the hose end to the pipeline may also beplaced at the second end of the hose.

The chamber accommodating the hose makes it possible to coat longpipelines by feeding the working medium thereto, the coating processbeing automated and its quality improved.

The availability of the hose fixing arrangements at the hose endsenables one to move the hose following the piston with any length of thepipeline, thereby increasing the speed of coating and diminishingauxiliary operations because the number of foundations pits and chambersaround the pipeline is reduced as the latter is coated.

It is also expedient that a drum with a hollow shaft and a flexible hosewound thereupon be mounted in the chamber, said hose accommodating aflexible tube by one end communicating via the drum hollow shaft withthe mortar feed system and by the other end communicating via throughducts with a cavity made in the piston, the latter having an annularprojection.

According to the invention, a second chamber communicating with theflowing medium feed system is mounted in the device. Said chamber housesa mechanism for placing and fixing the protector alloy strips which ismade from a piston with slots for the strips and rollers press-fittingthe strips in the formed coating.

The flexible tube may communicate with the mortar feed system via abranch pipe having a chamber accommodating an elastic plug, said chambercommunicating with the working medium feed system beyond the plug.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more apparent upon considering a detailedexemplary embodiment of the method of coating the internal surface ofthe pipeline with the cement-sand mortar and the device for effectingsame, according to the invention, references being made to theaccompanying drawings, wherein:

FIG. 1 is a schematic general view of the device for coating theinternal surface of the pipeline, a longitudinal section;

FIG. 2 shows the device of FIG. 1, the view taken along arrow A;

FIG. 3 is another schematic variant of the device, according to theinvention, feeding the mortar via the tube in the flexible hose;

FIG. 4 is a chamber with an elastic plug for removing the mortar fromthe hose;

FIG. 5 shows the device of FIG. 3, with a chamber arranged in thepipeline along the axis thereof;

FIG. 6 is a schematic general view of the device, according to theinvention and

FIGS. 7 and 8 are the variants of fixing the flexible hose end to thepipeline.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The method of coating the internal surface of the pipeline with thecement-sand mortar resides in that the coating is formed on the surfaceof a pipeline 1 (FIG. 1) by feeding and distributing a cement-sandmortar 2 on the internal surface of the pipeline by means of a movingpiston 3. A formed layer 4 of the mortar is pressed to and held on thepipeline surface with the aid of a flexible hose 5 (sheath) which by anend 6 is secured to the pipeline 1 and turned out before being pressedto the layer 4 of the mortar, the flexible hose 5 being laidsimultaneously with the formation of the layer 4 of the mortar. Theturned-out portion of the hose makes contact with the piston, as isshown in FIGS. 1, 3, 5, 8, to create a higher pressure in the hose whichdevelops a force pressing the latter to the layer 4 and prevents therupture of the hose. The flexible hose 5 is made from any prior artmaterial, including polyethylene.

The flexible hose 5 is fed, turned out and pressed to the layer 4 of themortar by means of a flowing medium (e.g., air) which is fed to a cavity7 being formed by the turned out portion of the hose 5, said flowingmedium (air) and the section of the hose 5 forming a device for movingthe mortar 2 and piston 3 along the pipeline 1.

Once the mortar has solidified, i.e., the coating has been formed, thesecured end 6 of the hose 5 is disconnected and removed by pumping theair between the hose 5 and the coating formed, said hose can be used atthe subsequent portions of the pipeline. For this purpose, the secondend of this hose is secured to the pipeline 1 and as the air is fedbetween the hose and the coating, the hose is disconnected and, as it isturned out, it is taken to the next portion of the pipeline.

If the flexible hose 5 is a component part of the coating, in this case,the hose 5 is not removed and longitudinal strips 8 of anelectrochemically soluble alloy of any known composition, e.g.,alluminum alloy, comprising (wt. %) magnesium 0.1-1, gallium 0.1 to 3.5,alluminium--the rest, can be press-fitted therein. The alloy of such acomposition ensures its dissolution in a neutral medium, e.g., freshwater, creating a negative electrochemical potential between the stripand the material (metal) of the pipeline, the alloy dissolution productsare deposited on the surface of the pipeline forming an oxide filmthereupon which protects the pipeline against corrosion where there arecracks in the coating.

To reduce the number of operations, as the coating is applied, theflexible tube 9 (FIGS. 3) is fed simultaneously with the flexible hose5; the cement-sand mortar is pumped to the piston 3 along said tube 9,the latter being arranged in the flexible hose 5. The remaining mortaris removed from the tube 9 by feeding an elastic plug 10 (FIG. 4)therethrough using an air flow with a subsequent washing of the tubewith water.

The device, effecting the method as claimed for coating the internalsurface of a pipeline with the cement-sand mortar, comprises a system 11(FIGS . 3, 5) for feeding the cement-sand mortar to the pipeline 1; thepiston 3 arranged in the pipeline 1 with an annular clearance 12 fordistributing the layer of the mortar along the internal surface of thepipeline 1; a chamber 13 disposed beyond the piston 3 in the directionof the application of the mortar, said chamber accommodating theflexible hose 5 wound on the drum 14. Any prior art system 15 forfeeding a flowing medium, e.g, air may be used.

The cement-sand mortar feed system 11 comprises the prior art pump forpumping over cement which communicates with the piston 3 of the pipeline1 by means of the tube 9 or with the pipeline via an opening 16 (FIGS.6-8).

The cement-sand mortar feed system 11 is mounted from the outside of thepipeline and feeds the mortar through the opening 16 into the pipelinebefore the piston 3. The cement-sand mortar may be fed between twopistons 3 and 17, as is shown in FIG. 1, which fact precludes the flowthereof along the pipeline.

The piston 3 can move in the pipeline by various means, e.g., with theair of a pull rope 18 connected with the prior art pull mechanism 19, asis shown in FIG. 6, or by feeding the flowing medium (air) from thesystem 15 to the turned-out portion of the hose 5, which affects thepiston 3 through the hose 5.

The cement-sand mortar may be pumped into a cavity 20 made in the piston3, as is shown in FIG. 3. The piston 3 is made stepwise or with anannular projection 21. In the step of a lesser diameter provision ismade for ducts 22 communicating with the cavity of the piston and thepipeline in the zone of the annular clearance 12. The mortar is fed viathe ducts 22 to the annular clearance 12 formed by the body of thepiston of the lesser step and the internal surface of the pipeline 1.

The chamber 13 with the flexible hose 5 wound on the drum 14 is mountedbeyond the piston 3 in the direction of the mortar application off thepipeline, as is shown in FIGS. 1, 3, or inside the pipeline, as is shownin FIG. 5. Before the hose 5 is wound on the drum 5, the flexible tube 9for feeding the cement-sand mortar is drawn into the hose, said tube 9is wound alongside the flexible hose 5 on the drum 14 (the layers of thehose 5 and flexible tube 9 are conventionally shown in FIGS. 3 and 5).One end of the tube 9 is fixed in the piston 3 and communicates via aduct with a cavity 20, the other end of the tube 9 passes through ahollow shaft 23 of the drum 14 and through a rotary seal 24 of and knownconstruction, communicates with the cement-sand feed system 11.

The end 6 of the flexible hose 5 is fitted with the arrangement forfixing it to the pipeline internal surface. This arrangement may haveany prior art construction, e.g., it may be made in the form of annularstrips 25 (FIG. 6) secured to the pipeline by means of bolts 26, ofhermetic elastic chambers 27 (FIG. 7), with a nipple, or sheaths 28(FIG. 8) from a magnetic elastic material, for example, rubber with aferrite filler. Before the end 6 of the hose is fixed to the pipeline,this end is turned out, as is shown in FIGS. 1, 3, 5-8, and then it isfixed. If the flexible hose 5 is removed after the solidification of themortar, this hose is usually used in subsequent portions of thepipeline. Therefore, the second end of such a hose is also fitted withthe arrangement to fix it to the pipeline, which is made analogously tothe above arrangements.

Arranged in the pipeline 1 beyond the chamber 13 is another chamber 29(FIG. 1) communicating with the flowing medium feed system 15. Disposedin the chamber 29 is a mechanism 30 for placing and fixing the strips 8made from an electrochemically soluble alloy, e.g., the alluminum alloyindicated hereinabove.

The mechanism 30 contains a piston 31 with rollers 32 being secured tothe front portion of said piston 31 facing the piston 3; the number ofsaid rollers 32 corresponds to that of simultaneously laid strips 8. Inthe piston 31 provision is made for slots 33 for the strips to pass.Made in the strips are tenons 34 which are pressed in the layer of thecement-sand mortar on the surface of the pipeline through the flexiblehose 5.

The flowing medium feed system 15 (FIG. 1) communicates with thechambers 13 and 29 by means of tubes 35 with solenoid valves 36 of anyprior art design mounted therein. A limit switch 37 contacting with thehose 5 serves to control the valves.

The flexible tube 9 communicates with the mortar feed system 11 via abranch pipe 38 (FIG. 4) having a chamber 39 communicating therewith,which accommodates the elastic plug 10. Beyond the plug 10 the chamber39 communicates with the flowing medium feed system 15.

The device as claimed operates as follows.

The end 6 (FIG. 1) of the hose 5 being reeled off the drum 14 is turnedout and secured to the internal surface of the pipeline 1.

Pressurized air (e.g., a pressure of 0.8 MPa) is pumped into the cavity7 formed by the turned out portion of the hose 5 using the system 15. Asa result, the hose 5 starts moving along the pipeline 1 pressing thepiston 3 which forces out the cement-sand mortar 2 to the annularclearance 12 wherein the layer 4 is formed. Upon the formation of thelayer 4, the hose 5 is pressed by the flowing medium (air) to theinternal surface of the pipeline 1. Due to the pressure of compressedair in the cavity 7 of the hose 5 the piston 3 (or the piston 3 and 17)moves together with the mortar 2 along the pipeline 1 forming a coatingof the cement-sand mortar 2 and the hose 5.

The piston 3 may be additionally moved along the pipeline 1 by means ofthe pull rope 18 (FIG. 6) using the pull mechanism 19.

As the mortar 2 is consumed, it is periodically pumped by the system 11into the cavity 20 of the piston 3 along the tube 9 or between thepistons 3 and 17, or directly before the piston 3, as is shown in FIGS.6-8.

If necessary, an additional electrochemical protection may be formed inthe pipeline in the following manner.

Once the whole hose 5 (FIG. 1) has been reeled off the drum 14, theswitch 37 switches the solenoid valves 36 and the air begins to enterthe cavity of the pipeline 1 disposed behind the piston 31 and shiftsthe latter along the pipeline 1, the rollers 32 being press-fitted viathe hose 5 in the layer 4 of the strip 8. The tenons 34 of the strips 8pierce through the hose 5 and enter the formed layer 4. In case theair-tightness of the protective coating (layer 4 and hose 5) isdisturbed, an electrochemical potential develops between the metal wallof the pipeline 1 and the strips 8 resulting in the dissolution of thestrips 8. The dissolution products are settled in the damaged places ofcoating and seal the latter, whereupon, the strips cease to be dissolveduntil the next breakdown of the protective coating.

In the event of a failure in feeding the cement-sand mortar 2 along thetube 9, or upon the completion of application of the protective coating,the pressure of the cement-sand mortar in the tube 9 is declined andowing to the pressure of compressed air in the chamber 39 the plug 10(FIG. 4) begins to move along the tube 9 and remove the mortartherefrom, thereby preventing the possible solidification of thecement-sand mortar in the tube 9.

The hose 5 (FIG. 1) may serve both as a component part of the coatingand as a technological hose which is removed upon the solidification ofthe layer 4. In this case, the hose 5 is removed and may be used at asubsequent portion of the pipeline. For this purpose, the end of thehose 5 is disconnected from the pipeline 1 and the second end thereofarranged in the direction of the formation of the coating is secured tothe pipeline 1. Compressed air is pumped by means of the system 15between the formed layer 4 and the hose 5. As a result, the hose 5 isgradually turned inside out in the place where its second end is fixedto the pipeline and is moved to the next portion of the pipeline 1pressing and holding the layer 4 being formed on the internal surface ofthe pipeline 1 until it is solidified.

The method of coating the internal surface of a pipeline with acement-sand mortar and a device for effecting same may be used inpublic, agricultural and industrial water supply, as well, as to protectchemical, oil- and gas pipelines against corrosion. The method anddevice as claimed may be used for applying a 1 to 50 mm thick coating inpipelines of 100 to 6000 mm in diameter.

We claim:
 1. Method of coating the internal surface of a pipeline with acement-sand mortar, comprising the steps of forming a layer (4) of thecement-sand mortar (2) on the internal surface of a pipeline (1);pressing a flexible hose (5) having two ends against said mortar layer(4); connecting a turned out end of said hose to the pipeline (1);compressing a flowing medium in the turned out portion of the hose (5);under pressure of the flowing medium the flexible hose, turning out,moving along the pipeline, and pressing against said layer of thecement-sand mortar formed on the pipeline surface; disposing the piston(3) in the pipeline (1) ahead of the turned out portion of the hose (5)with an annular clearance (12) with respect to the pipeline (1); feedingcement-sand mortar (2) is through the annular clearance (12) between theinternal surface of the pipeline (1) and the piston (3) thus formingsaid mortar layer (4) on the surface of the pipeline, the turned outportion of the flexible hose being permanently maintained in contactwith the piston (3) to move it under the action of the flowing medium.2. A method as in claim 1, characterized in that the flexible hose (5)upon the solidification of the mortar (2) on the pipeline surface isremoved by feeding the flowing medium between the hose (5) and themortar layer (4) and having fixed the second end of the hose to thepipeline so that as it is fed it is gradually turned out, to asubsequent portion of the pipeline.
 3. A method as in claim 2,characterized in that a tube is arranged in the flexible hose, said tubebeing fed together with the hose to the pipeline and serving to pump themortar to the piston.
 4. A method as claimed in claim 3, furthercomprising the step of removing remaining motar is removed from the tubein the pipeline by feeding an elastic plug therethrough using an airflow with a subsequent washing of the tube with water.
 5. A method as inclaim 1, characterized in that longitudinal strips (8) from anelectrochemically soluble alloy are pressed in the layer (4) of themortar held by the flexible hose (5).
 6. A method as in claim 5,characterized in that a tube is arranged in the flexible hose, said tubebeing fed together with the hose to the pipeline and serving to pump themortar to the piston.
 7. A method as claimed in claim 6, furthercomprising the step of removing remaining motar is removed from thepipeline by feeding an elastic plug therethrough using an air flow witha subsequent washing of the tube with water.
 8. A method as in claim 1,characterized in that a tube (9) is arranged in the flexible hose (5),said tube being fed together with the hose (5) to the pipeline (1) andserving to pump the mortar (2) to the piston (3).
 9. A method as claimedin claim 8, further comprising the step of removing remaining mortarfrom the tube (9) in the pipeline (1) by feeding an elastic plug (10)therethrough using an air flow with a subsequent washing of the tubewith water.
 10. A device for coating the internal surface of a pipelinewith a cement-sand mortar, comprising a system (11) for feeding thecement-sand mortar into the pipeline; a chamber (13) with a flexiblehose (5), having two ends, disposed therein, one end of said flexiblehose being provided with an arrangement for attachment to the pipelineand being preliminary turned out; a system (15) for feeding the flowingmedium which communicates with a space formed by the turned out hose; apiston (3) disposed in the pipeline ahead of said turned out portion ofsaid hose in permanent contact with said turned out portion of saidhose, said piston (3) having a diameter less than the inner diameter ofthe pipeline and being provided with projections (21) contacting withthe internal surface of the pipeline and maintaining a preset annularclearance (12) between said piston and the pipeline surface, saidflexible hose (5) and the flowing medium forming means moving the pistonalong the pipeline so that the cement-sand mortar is pressed out throughsaid annular clearance (12) between said piston and the pipeline therebyforming a cement-sand layer on the surface of the pipeline, which layeris then supported by the turned-out portion of said flexible hose (5).11. A device as claimed in claim 10, characterized in that in thechamber (13) provision is made for a drum (14) with a hollow shaft and aflexible hose (5) wound thereupon accommodating a flexible tube (9) byone end communicating with the mortar feed system (11) via the drum (14)hollow shaft and by the other end communicating via through ducts with acavity (20) made in the piston (3), said piston (3) having an annularprojection.
 12. A device as claimed in any of the claim 11,characterized in that a second chamber (29) is arranged whichcommunicates with the flowing medium feed system (15), said secondchamber accommodating the mechanism for placing and fixing strips (8)from an electrochemically soluble alloy, said mechanism made up from apiston (31) with slots (33) for the strips to pass and rollers (32) forpress-fitting said strips (8) in the coating formed.
 13. A device asclaimed in claim 11, characterized in that the flexible tube (9)communicates with the mortar feed system (11) via a branch pipe (38),having a chamber (39) accommodating an elastic plug (10), the chamber(39) communicating with the flowing medium feed system (11) beyond saidplug (10).